Vehicle imaging system, vehicle imaging method and device, program, and recording medium

ABSTRACT

A system includes a laser displacement sensor which is provided on a shoulder of a roadway, emits a laser beam which scans a roadway space in a height direction thereof, receives a beam reflected by an object which is present in the roadway space, and measures a distance up to a reflection point on the object, at which the laser beam was reflected; and a vehicle window detection device that detects a window of the vehicle based on the distance measured by the laser displacement sensor. The vehicle window detection device detects the window of the vehicle based on a change in a distance in a horizontal direction from the laser displacement sensor to the reflection point after the vehicle in the roadway space was detected.

This application is a National Stage Entry of PCT/JP2013/078352 filed onOct. 18, 2013, which claims priority from Japanese Patent Application2012-231675 filed on Oct. 19, 2012, the contents of all of which areincorporated herein by reference, in their entirety.

TECHNICAL FIELD

The present invention relates to a vehicle window detection system, avehicle window detection method, a vehicle window detection device, aprogram, and a recording medium.

BACKGROUND ART

Road traffic detection is performed so that drivers who drive individualvehicles, a manager who manages operation of the vehicles, a trafficmanager, and a road manager understand the road traffic situation bymeans of various sensors and carry out actions so as to maintain a safe,smooth, and comfortable traveling environment.

As a known technique in the relevant technical field, Patent Document 1discloses a system that efficiently and accurately examines parkedvehicles by utilizing a running vehicle for examination. Specifically,in the system, data for a target object on a road, which is imaged by alaser scanner built in a measuring vehicle which is travelling on theroad, is received.

The above system has a side data extraction unit which extracts data ofa side (surface) of a parked vehicle which is parked on a road, based onthe data imaged by the laser scanner, and a parked vehiclepresence/absence determination unit that determines the presence orabsence of a parked vehicle, based on the extracted side surface data ofthe parked vehicle.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Publication of Japanese Patent No. 3,740,531.

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

In a traffic management system, the interior of each vehicle may beimaged from the outside of the vehicle for a variety of purposes such asdetermination of travel regulation or traveling lane compliance withreference to the number of passengers, entry passenger management ofentry vehicles, scanning to find a vehicle used in a crime, anddetermination about compliance status for the legal number ofpassengers. In the imaging, the status of the passenger seat and thedriver's seat can be known by means of imaging through the windshieldfrom the front of the vehicle.

However, when imaging the interior of the vehicle through the windshieldfrom the front of the vehicle, the status of the rear seat may not beaccurately known because the rear seat may be hidden by each head ofpersons who are sitting in the driver's seat and the passenger seat, theheadrests of the seats, or the like.

Therefore, it is estimated that the status of the entire interior of thevehicle can be known utilizing a system which images the interiorthrough a window from a side of the vehicle.

However, the position of each window of a vehicle varies depending onthe model to which the vehicle belongs. Therefore, to implement such asystem, it is required to accurately detect a window of a targetvehicle. To meet such a requirement, the technology described in PatentDocument 1 can determine the presence or absence of a vehicle, butcannot detect a window of the vehicle.

An object of the present invention is to provide a vehicle windowdetection system, a vehicle window detection method, a vehicle windowdetection device, a program, and a recording medium, which solve theabove-described problem.

Means for Solving the Problem

In order to solve the above problem, a vehicle window detection systemprovided by the present invention has:

a laser displacement sensor which is provided on a shoulder of aroadway, emits a laser beam which scans a roadway space in a heightdirection thereof, receives a beam reflected by an object which ispresent in the roadway space, and measures a distance up to a reflectionpoint on the object, at which the laser beam was reflected; and

a vehicle window detection device that detects a window of the vehiclebased on the distance measured by the laser displacement sensor.

The vehicle window detection device detects the window of the vehiclebased on a change in a distance in a horizontal direction from the laserdisplacement sensor to the reflection point after the vehicle in theroadway space was detected.

The present invention also provides a vehicle window detection methodutilizing a laser displacement sensor which is provided on a shoulder ofa roadway, emits a laser beam which scans a roadway space in a heightdirection thereof, receives a beam reflected by an object which ispresent in the roadway space, and measures a distance up to a reflectionpoint on the object, at which the laser beam was reflected. The methodincludes detecting a window of a vehicle based on a change in a distancefrom a position of the laser displacement sensor in a horizontaldirection to a position of the reflection point in the horizontaldirection, after the vehicle in the roadway space was detected.

The present invention also provides a vehicle window detection devicethat detects a window of a vehicle utilizing a laser displacement sensorwhich is provided on a shoulder of a roadway, emits a laser beam whichscans a roadway space in a height direction thereof, receives a beamreflected by an object which is present in the roadway space, andmeasures a distance up to a reflection point on the object, at which thelaser beam was reflected. The device detects the window of the vehiclebased on a change in a distance from a position of the laserdisplacement sensor in a horizontal direction to a position of thereflection point in the horizontal direction, after the vehicle in theroadway space was detected.

The present invention also provides a program that makes a computerexecute a function of detecting a window of a vehicle utilizing a laserdisplacement sensor which is provided on a shoulder of a roadway, emitsa laser beam which scans a roadway space in a height direction thereof,receives a beam reflected by an object which is present in the roadwayspace, and measures a distance up to a reflection point on the object,at which the laser beam was reflected. In the program, the window of thevehicle is detected based on a change in a distance from a position ofthe laser displacement sensor in a horizontal direction to a position ofthe reflection point in the horizontal direction, after the vehicle inthe roadway space was detected.

The present invention also provides a recording medium that stores aprogram which makes a computer execute a function of detecting a windowof a vehicle utilizing a laser displacement sensor which is provided ona shoulder of a roadway, emits a laser beam which scans a roadway spacein a height direction thereof, receives a beam reflected by an objectwhich is present in the roadway space, and measures a distance up to areflection point on the object, at which the laser beam was reflected.In the program, the window of the vehicle is detected based on a changein a distance from a position of the laser displacement sensor in ahorizontal direction to a position of the reflection point in thehorizontal direction, after the vehicle in the roadway space wasdetected.

Effect of the Invention

As clearly understood by the above explanation, in accordance with thepresent invention, with reference to image data of the interior of avehicle on a roadway, which was imaged through a glass window of thevehicle, it is possible to accurately know the state of a rear seat ofthe vehicle on the roadway, regardless of persons in the vehicle orloading situation of vehicle equipment or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the overall structure of a vehiclewindow detection system according to an embodiment of the presentinvention.

FIG. 2 is a diagram utilized to explain the imaging operation of thevehicle window detection system according to the embodiment of thepresent invention when a vehicle enters an imaging field.

FIG. 3 is a diagram utilized to explain the vehicle detection operationof the vehicle window detection system according to the embodiment ofthe present invention, for individual cases.

FIG. 4 is a diagram utilized to explain the operation, for individualcases, of scanning a detection target by a laser displacement sensor 130by means of a laser beam.

MODE FOR CARRYING OUT THE INVENTION

Below, embodiments of the vehicle window detection system, the vehiclewindow detection method, and the vehicle window detection device will beexplained in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall structure of a vehiclewindow detection system 100 according to an embodiment of the presentinvention. The vehicle window detection system 100 shown in FIG. 1 has avehicle window detection device 110 and a laser displacement sensor 130of a reflection type.

The laser displacement sensor 130 is displaced on a shoulder of a roadand emits a laser beam from a light emitting element in a manner suchthat a roadway space is scanned by the laser in the vertical direction.A (laser) beam reflected by an object which is present in the roadwayspace is received by a light receiving element so as to measure thedistance up to the reflection point on the object, at which the laser isreflected.

The vehicle window detection device 110 detects a window of each vehiclebased on the distance measured by the laser displacement sensor.

The system may further include a camera C and an infrared projector (notshown).

Hereinafter, the general function of the vehicle window detection system100 according to the present embodiment will be explained.

The vehicle window detection system 100 of the present embodimentdetects the entry of a vehicle V using the laser displacement sensor 130of the reflection type and detects the position of a glass window of thevehicle V utilizing a property of a laser beam such that the beam passesthrough the glass window of the vehicle V.

At the timing at which the position of the glass window of the vehicle Vhas been detected, a trigger for imaging is output to the camera C.Therefore, the state of the interior of the vehicle V can be reliablyimaged through the glass window of the vehicle V.

FIG. 2 is a diagram utilized to explain the imaging operation of thevehicle window detection system 100 when a vehicle enters an imagingfield. Hereinafter, with reference to FIG. 1, the imaging operation ofthe vehicle window detection system 100 (for the entry vehicle) will beexplained utilizing FIG. 2, in accordance with the progress status asshown by steps (a) to (d).

First, in step (a), on a principle of the laser beam emitted from thelaser displacement sensor 130 being reflected by an ordinary vehicle,the vehicle window detection device 110 measures the distance betweenthe laser displacement sensor 130 and the vehicle V (in this step, thevehicle V has not yet been determined to be a vehicle).

Next, in step (b), when the measured distance becomes less than or equalto a threshold which is predetermined for the present device, thevehicle window detection device 110 determines that the vehicle V to bea vehicle.

In the next step (c), the vehicle window detection device 110 detects acandidate for a window of the vehicle V.

An employed detection method is based on a principle that when thewindow of the vehicle V passes in front of the laser displacement sensor130, the distance between the laser displacement sensor 130 and thevehicle V, which is measured by means of the reflection of the laserbeam emitted from the laser displacement sensor 130, has differentvalues for the window part and the vehicle body of the vehicle V.

In the next step (d), for the detected candidate for the window of thevehicle V, the vehicle window detection device 110 verifies whether apredetermined determination condition is satisfied.

More specifically, the determination condition for the verifying processis whether or not (i) the position of the window as the candidate in thevertical direction is greater than or equal to a predetermined thresholdh1 and also less than or equal to another predetermined threshold h2,and (ii) the size of the window of the vehicle V in the verticaldirection is greater than or equal to a width h3.

Further, when the determination condition described above has beencontinued over a predetermined time t1, the vehicle window detectiondevice 110 determines the relevant candidate window of the vehicle V toan actual window of the vehicle V.

Immediately after determining that the candidate window of the vehicle Vto the window of the vehicle V, the vehicle window detection device 110sends a trigger for the imaging to the camera C. At the same time, thevehicle window detection device 110 outputs a trigger for the lightemission to the infrared projector (not shown).

FIG. 3 is a diagram utilized to explain the vehicle detection operationof the vehicle window detection system 100 according to the embodimentof the present invention, for individual cases. Hereinafter, withreference to FIGS. 1 and 2, the vehicle detection operation of thevehicle window detection system 100 in the present embodiment, byutilizing FIG. 3, for individual cases (as shown by (a) to (c)).

Here, in the measurement using the laser displacement sensor 130, withgiven “a” which is a measured value of the distance from the laserdisplacement sensor 130 to the vehicle body, the height up to thevehicle body viewed from the laser displacement sensor 130 (i.e.,vertical distance to the vehicle body) is b (b=a×sin θ). In addition,the distance from the laser displacement sensor 130 to the vehicle body(i.e., horizontal distance to the vehicle body) is c (c=a×cos θ).

In the measurement process of each case explained below, it is assumedthat a vertical distance computation unit (not shown) of the vehiclewindow detection device 110 computes the above-described verticaldistance and a horizontal distance computation unit (not shown) of thevehicle window detection device 110 computes the above horizontaldistance.

Also in the measurement process of each case, the measurement utilizingthe laser displacement sensor 130 is repeated several times at regulartemporal intervals.

First, in case (a) where there is no vehicle on the road, the laserdisplacement sensor 130 measures the reflection from the road surface,and thus “measured value b1 for the first time”=“measured value b2 forthe second time” (there is no change in the measured value).

Next, in case (b), when the vehicle has entered, the laser beam from thelaser displacement sensor 130 is reflected by the body of the vehicle,and thus “measured value b1 for the first time”>“measured value b2 afterthe entry”. That is, the measured value of the height to the vehiclebody viewed from the laser displacement sensor 130 has changed, so thatthe vehicle window detection device 110 determines that a vehicle hasentered in this case.

If the above status has continued, the vehicle window detection device110 determines that the vehicle is passing now and measures a measuredvalue c3 in the horizontal direction.

Hereinafter, in case (c), when a windowpane of the vehicle passes,measured value c3>“measured value c2 (in the horizontal direction) incase (b)”.

If such a status has continued, the vehicle window detection device 110determines that a window of the vehicle has been detected and outputs atrigger for imaging to the camera C.

FIG. 4 is a diagram utilized to explain the operation (for each case) ofscanning a detection target by the laser displacement sensor 130 bymeans of a laser beam. Hereinafter, with reference to FIGS. 1 to 3, theoperation of scanning a vehicle (as the detection target) by the laserdisplacement sensor 130 utilizing the laser beam will be explained usingFIG. 4, for the individual cases (as indicated by “(b)” and “(c)” in thefigures).

In the figures, if it is assumed that the scanning period of the laserdisplacement sensor 130 is 20 ms and the entry speed of the vehicle is40 km/h, then the scanning interval (i.e., length for each scan) isapproximately 0.22 m.

First, in case (b) in which a portion (of the vehicle) which includes nowindow passes, there is no temporal change in the distance from thelaser displacement sensor 130 to the vehicle body and thus a constantvalue is maintained substantially.

Next, in case (c) in which a portion (of the vehicle) which includes awindow passes, there is a temporal change in the distance from the laserdisplacement sensor 130 to the vehicle body because the window portionof the vehicle passes.

In the vehicle window detection method of the present invention, in theconfiguration of the vehicle window detection system 100 describedabove, the vehicle window detection device 110 and the laserdisplacement sensor 130 search for each vehicle on a roadway based onresults of measurement utilizing a laser beam. In addition, the vehiclewindow detection device 110 determines the position of a windowpane ofthe vehicle based on a change in the above-described measurement resultsduring a time which has elapsed.

According to such a determination, the vehicle window detection device110 can send the camera C an instruction to image the interior of thevehicle through the relevant glass window so that the state of theinterior of the vehicle can be reliably imaged. The above measurementresults include the horizontal distance and the vertical distancebetween the laser displacement sensor 130 and the vehicle.

Further, in the structure of the vehicle window detection system 100described above, the vehicle window detection device of the presentinvention detects the position of a glass window of a vehicle on aroadway, based on a change in the horizontal distance between the laserdisplacement sensor 130 and the vehicle along a time which has elapsed.

Additionally, in the vehicle window detection device 110, the computerprogram of the present invention executes and controls the abovedetection method of detecting a glass window of a vehicle on a roadway,based on a change in the horizontal distance between the laserdisplacement sensor 130 and the vehicle along a time which has elapsed.

The recording medium of the present invention is a recording medium thatstores the above computer program.

According to the vehicle window detection system 100 in the embodimentof the present invention, the interior of the vehicle can be imagesthrough the glass window at the exactly detected timing at which a glasswindow portion of the vehicle on the roadway is present at a positionmost suitable for the imaging. In addition, the device has a simplestructure and can be installed easily. Therefore, the vehicle windowdetection system 100 according to the embodiment of the presentinvention can be preferably applied to monitoring of the interior ofeach vehicle on a road.

The vehicle window detection system 100 according to the embodiment ofthe present invention is also preferably applied to and can exhibit aspecial effect on scanning to find a vehicle used in a crime,determination about compliance status for the legal number ofpassengers, determination about travel regulation or traveling lanecompliance with reference to the number of passengers, entry passengermanagement of entry vehicles, or the like.

In a system as another embodiment of the present invention, the vehiclewindow detection device 110 of the vehicle window detection system 100has an additional function of determining the shape of the vehicle basedon information obtained from the laser displacement sensor 130.

Priority is claimed on Japanese Patent Application No. 2012-231675,filed on Oct. 19, 2012, all contents of which are incorporated herein byreference.

INDUSTRIAL APPLICABILITY

According to the present invention, with reference to image data of theinterior of a vehicle on a roadway, which was imaged through a glasswindow of the vehicle, it is possible to accurately know the state of arear seat of the vehicle on the roadway, regardless of persons in thevehicle or loading situation of vehicle equipment or the like.

REFERENCE SYMBOLS

-   100 vehicle window detection system-   110 vehicle window detection device-   130 laser displacement sensor-   C camera-   V vehicle

What is claimed is:
 1. A vehicle imaging system comprising: a laserdisplacement sensor which is provided on a shoulder of a roadway, emitsa laser beam which scans a roadway space in a height direction thereof,receives a beam reflected by an object which is present in the roadwayspace, and measures a distance up to a reflection point on the object,at which the laser beam was reflected; a vehicle window detection devicethat detects a window of a vehicle based on the distance measured by thelaser displacement sensor, and a camera that images the vehicle,wherein: the vehicle window detection device detects the window of thevehicle based on a measured change in a distance in a horizontaldirection from the laser displacement sensor to the reflection pointafter the vehicle in the roadway space was detected; wherein if thedistance in the horizontal direction from the laser displacement sensorto the reflection point has been measured so as to increase from a firstmeasured distance between the laser displacement sensor and a vehiclebody of the vehicle in the roadway space to a second measured distancebetween the laser displacement sensor and an interior of the vehiclethrough the window of the vehicle, then the vehicle window detectiondevice determines that the window of the vehicle has been detected; andwherein the vehicle imaging system is configured to, based on the windowof the vehicle being, detected, send a trigger for imaging an interiorof the vehicle through the detected window from a side of the vehicle tothe camera.
 2. The vehicle imaging system in accordance with claim 1,wherein the vehicle window detection device: computes the distance inthe horizontal direction from the laser displacement sensor to thereflection point based on the distance measured by the laserdisplacement sensor; and detects the window of the vehicle based on achange in the computed distance.
 3. The vehicle imaging system inaccordance with claim 1, wherein the vehicle window detection devicedetects the vehicle in the roadway space based on a change in a distancein a vertical direction from the laser displacement sensor to thereflection point and then detects the window of the vehicle.
 4. Thevehicle imaging system in accordance with claim 3, wherein if thedistance in the vertical direction from the laser displacement sensor tothe reflection point has become shorter than a height of the laserdisplacement sensor measured from a surface of the roadway, then thevehicle window detection device determines that the window of thevehicle has been detected.
 5. The vehicle imaging system in accordancewith claim 3, wherein the vehicle window detection device: computes thedistance in the vertical direction from the laser displacement sensor tothe reflection point based on the distance measured by the laserdisplacement sensor; and detects the vehicle in the roadway space basedon a change in the computed distance.
 6. A vehicle imaging methodutilizing a laser displacement sensor which is provided on a shoulder ofa roadway, emits a laser beam which scans a roadway space in a heightdirection thereof, receives a beam reflected by an object which ispresent in the roadway space, and measures a distance up to a reflectionpoint on the object, at which the laser beam was reflected, wherein: themethod includes: detecting a window of a vehicle based on a measuredchange in a distance from a position of the laser displacement sensor ina horizontal direction to a position of the reflection point in thehorizontal direction, after the vehicle in the roadway space wasdetected; wherein if the distance in the horizontal direction from thelaser displacement sensor to the reflection point has been measured soas to increase from a first measured distance between the laserdisplacement sensor and a vehicle body of the vehicle in the roadwayspace to a second measured distance between the laser displacementsensor and an interior of the vehicle through the window of the vehicle,then it is determined that the window of the vehicle has been detected;and sending a trigger to a camera for imaging an interior of the vehiclethrough the detected window from a side of the vehicle when the windowof the vehicle has been detected from the side of the vehicle such thatthe camera images the vehicle.
 7. A vehicle imaging device that detectsa window of a vehicle utilizing a laser displacement sensor which isprovided on a shoulder of a roadway, emits a laser beam which scans aroadway space in a height direction thereof, receives a beam reflectedby an object which is present in the roadway space, and measures adistance up to a reflection point on the object, at which the laser beamwas reflected, wherein: the device detects the window of the vehiclebased on a measured change in a distance from a position of the laserdisplacement sensor in a horizontal direction to a position of thereflection point in the horizontal direction, after the vehicle in theroadway space was detected; wherein if the distance in the horizontaldirection from the laser displacement sensor to the reflection point hasbeen measured so as to increase from a first measured distance betweenthe laser displacement sensor and a vehicle body of the vehicle in theroadway space to a second measured distance between the laserdisplacement sensor and an interior of the vehicle through the window ofthe vehicle, then the device determines that the window of the vehiclehas been detected; and wherein the vehicle imaging device is configuredto, based on the window of the vehicle being detected, send a triggerfor imaging an interior of the vehicle through the detected window froma side of the vehicle to a camera such that the camera images thevehicle.
 8. A non-transitory computer recording medium that stores aprogram which makes a computer execute functions of: detecting a windowof a vehicle utilizing a laser displacement sensor which is provided ona shoulder of a roadway, emits a laser beam which scans a roadway spacein a height direction thereof, receives a beam reflected by an objectwhich is present in the roadway space, and measures a distance up to areflection point on the object, at which the laser beam was reflected,wherein the window of the vehicle is detected based on a measured changein a distance from a position of the laser displacement sensor in ahorizontal direction to a position of the reflection point in thehorizontal direction, after the vehicle in the roadway space wasdetected; wherein if the distance in the horizontal direction from thelaser displacement sensor to the reflection point has been measured soas to increase from a first measured distance between the laserdisplacement sensor and a vehicle body of the vehicle in the roadwayspace to a second measured distance between the laser displacementsensor and an interior of the vehicle through the window of the vehicle,then it is determined that the window of the vehicle has been detected;and sending a trigger to a camera for imaging an interior of the vehiclethrough the detected window from a side of the vehicle when the windowof the vehicle has been detected from the side of the vehicle, such thatthe camera images the vehicle.